1. Field of the Invention
This invention relates to the production of mushroom spawn and particularly to sterilizable bags, for use in the production of mushroom spawn. More especially the invention provides a sterilizable bag for mycelium growing medium. The growing medium, usually inoculated with mycelium, is fed into the bag, which is then sealed and stored under incubating conditions for growth of the mycelium to produce a bag of mushroom spawn which can be shipped directly for use by the mushroom grower and is a convenient package for sale. Inoculation may be carried out with the growing medium already in the bag.
The invention also relates to an improved method for producing mushroom spawn in such sterilizable bags.
2. Description of the Prior Art
In one process currently in use mushroom spawn is produced in bags, by filling a bag with particulate nutrient material for example grains of rye, sterilizing the bag and the nutrient material, and then inoculating with mycelium before sealing the bag under sterile conditions, and finally leaving the contents of the bag to incubate. In order to grow mycelium through the medium in the bag, oxygen is necessary and carbon dioxide is given off. It is also necessary to maintain sterile conditions during growth, so that the mushroom spawn is not comtaminated. In the present practice mushroom spawn is produced by growing mycelium in rye in sealed plastic bags. One wall of each bag includes a paper panel which acts as a bacterial filter but through which both oxygen and carbon dioxide can pass.
Such bags are intended as the final package for delivery of the mushroom spawn product to the customer, but have the disadvantage that water present during growth wets the paper strip which loses strength and becomes a poor bacterial filter.
It is sometimes necessary to shake the bag during incubation. This is thought to draw infection into the nutrient medium through the paper strip whose bacterial filtering qualities are deteriorating. Also this process is labour intensive and requires strong bags to withstand the shaking.
It is a main object of the present invention to provide an improved sterilizable bag, particularly for mycelium growing medium, which does not suffer the disadvantage of the known bags and which permits the mycelium to grow right through the medium in the bag without the need for shaking the bag during the growth period.